The Doctor takes Donna to the Ood-Sphere in the year 4126. This is the
planet where Ood are bred by the Ood Operations company, to be
distributed as willing servants to humanity throughout the cosmos. But
something is going wrong with the Ood: their eyes are turning red,
leading to acts of murder and ultimately a feral state. The search for
answers leads the time travellers to uncover the terrible truth behind
the origins of the Ood race.

Production

Keith Temple had gotten his start in television by writing for
documentaries, before contributing to programmes such as
Emmerdale, Casualty, EastEnders and Byker
Grove. Temple had been a Doctor Who fan in his youth, and his
partner, Morag Bain, had worked with Doctor Who executive
producer Russell T Davies on the family series Children's Ward.
As a result, Temple was able to forward Davies his script for the
forthcoming production Angel Cake. On this basis, during the
summer of 2006 Davies invited Temple to discuss the possibility of
writing for Doctor Who. Some thought was given to assigning him a
slot for the programme's 2007 season, but it was ultimately decided to
bring Temple on board for 2008 instead.

Davies had long been keen to revisit the Ood, a servitor race introduced
in 2006's The Impossible Planet which
had proved popular with the production team and the public alike.
Indeed, he had previously considered incorporating the Ood into the 2007
adventure 42. In preparing for the 2008
season, Davies contemplated devoting a two-part slot to an Ood
adventure, but ultimately decided that the storyline would work better
if it was not overcomplicated. The chief casualty was an extended
sequence set in caves beneath the planet's surface, in which the Doctor
searches for the giant Ood brain. It was this Ood adventure that Davies
offered Temple; entitled Planet Of The Ood, it was intended to be
the season's second episode.

It was thought that Ida Scott from The Impossible Planet might appear

Temple was asked to set his adventure on an ice planet, because this was
an environment not yet explored since Doctor Who's revival in
2005. It was also suggested that the character of Ida Scott from The Impossible Planet / The Satan
Pit feature prominently in Planet Of The Ood. Ida would
now be a member of an investigative team looking into conditions on the
Ood-Sphere, who would be dismayed to discover that her estranged father
is now involved with Ood Operations -- although it would later be
revealed that he is secretly acting on behalf of the Ood. In the end,
however, it was agreed that Temple should develop entirely new
characters for Planet Of The Ood.

When Temple began working on his script, Davies was still devising a new
companion who would join the Doctor for the 2008 season. Since both Rose
Tyler and Martha Jones had been young women with a romantic attachment
to the Doctor, Davies now sought a completely different dynamic. He had
been very fond of the interaction between the Doctor and Donna Noble in
The Runaway Bride, the 2006 Christmas
special, and began thinking in terms of pairing the Doctor with a more
mature character who would be less of a willing foil. Indeed, Davies
privately wanted to bring Donna back as an ongoing character, but
assumed that there was no chance that actress Catherine Tate would be
available for nine months' filming. Tate was a high-profile performer in
her own right, having already successfully headlined several seasons of
her self-titled comedy series, and Davies knew that she constantly in
demand.

Instead, Davies decided to craft a new character with Donna-like
tendencies. This became Penny Carter, a journalist who would meet the
Doctor after discovering that Gary, the boyfriend with whom she's
living, is cheating on her. Davies envisaged Penny as having a nagging
mother (possibly named Moira) and a grandfather who was a more
idealistic stargazer. Davies began seriously developing Penny during
February 2007.

In early March, however, he learned from BBC Head of Fiction Jane
Tranter that she had recently met with Tate, and raised the possibility
of the actress' return to the role of Donna. By this point, Davies was
considering bringing back all of the Doctor's past companions for the
2008 finale, and had hoped that Tate might be available for this. To his
surprise, Tranter informed him that Tate was actually interested in
joining Doctor Who as Donna for the entire season. Davies
responded enthusiastically to the proposal, and on March 13th, executive
producer Julie Gardner formally offered Tate a contract for all thirteen
episodes of the 2008 season. Tate officially accepted on the 19th. Plans
to introduce Penny were immediately scrapped, with Donna taking her
place. Tate's return to Doctor Who was announced to the press on
July 3rd.

Russell T Davies felt that the sombre story would
undermine concerns about Donna Noble being too farcical

Meanwhile, Temple had continued drafting Planet Of The Ood. Its
positioning as the season's second episode had now taken on a new
importance: since it was a relatively sombre and serious story, Davies
felt that it would undermine concerns about Donna being too farcical a
character to serve as an ongoing companion. By early August, however,
Davies raised concerns that Planet Of The Ood had in fact become
too grim to appear so early in the broadcast schedule. It was decided to
interchange it in the running order with The
Fires Of Pompeii, making it the season's third episode instead.
Some of Temple's influences were indeed very dark, such as the 2002
horror film 28 Days Later, which inspired the Ood's feral
state. On the other hand, the script also included a nod to the fact
that Davies' original conception of the Ood had been inspired by the
title aliens from the 1964 serial The
Sensorites. It was now suggested that the Ood-Sphere and the
Sense-Sphere were actually planets in the same solar system.

The first recording block of the new production schedule consisted
solely of the 2007 Christmas special, Voyage Of
The Damned. Planet Of The Ood was inserted into Block
Two, alongside The Unicorn And The Wasp;
these would therefore serve as Tate's reintroduction to filming on
Doctor Who, almost one year to the day after she finished work on
The Runaway Bride. The director for
these two episodes would be Graeme Harper, whose most recent Doctor
Who work included 42 and Utopia for the previous season. Since then,
Harper had helmed Whatever
Happened To Sarah Jane? for the first season of The Sarah
Jane Adventures. Producing Block Two would be Susie Liggat, who had
also filled the producer's chair for the double-banked Human Nature / The Family Of Blood
the year before. This time, Liggat would be filling in for regular
producer Phil Collinson in order to give Collinson time to devote to the
logistically-complex Voyage Of The
Damned and Block Three -- The Fires Of
Pompeii -- which featured several days of filming in Italy. As
usual, Collinson would instead be credited as an executive producer on
the Block Two episodes.

Recording for Planet Of The Ood began on August 21st, with two
days at the Upper Boat Studios capturing material in the sales reception
area. Shots of an Ood for the advertisement which opens the episode were
also performed on the 21st. The surface of the Ood-Sphere was actually
Trefil Quarry in Trefil, Gwent, where filming took place on the 23rd. On
August 24th and 27th, scenes in the container warehouse were recorded in
a hangar at RAF St Athan in Barry. Cast and crew remained in Barry from
the 28th to the 31st, when material in the Ood cells and on the grounds
of Ood Operations were filmed at Aberthaw Cement Works. The first day of
September saw production return to Upper Boat, when various effects
shots and the sequences of Bartle's death and of Donna inside the Ood
container were taped alongside some of those in Halpen's office. The
latter were finished on the 3rd.

The long gap after the 2008 season was planned to help
avert audience fatigue with Doctor Who

The same day, the BBC confirmed that Doctor Who had been renewed
for a fifth season -- but revealed that this would not air until the
spring of 2010. During the twenty or so months following the conclusion
of the 2008 season, a number of specials would air instead, and these
would continue to feature David Tennant as the Doctor and Davies as the
show's executive producer. This unusual statement about Doctor
Who's longterm future was prompted by the Royal Shakespeare
Company's announcement at the end of August that Tennant would be
appearing in Hamlet and Love's Labour's Lost throughout
the latter half of 2008. Since this coincided with Doctor Who's
normal production dates, intense speculation followed about the
programme's fate. In fact, the gap between seasons had been planned for
quite some time: Davies worried that the public would eventually become
fatigued with Doctor Who, and felt that after four years on the
air, a hiatus of sorts would discourage complacency in the programme's
viewers. He also anticipated that he would be leaving Doctor Who
around that time, and a year without a full season would facilitate a
smoother transition to the next showrunner. A subsidiary benefit of this
scheme was Tennant's availability to return to the theatre, something he
had been eager to do for some time.

Meanwhile, production on Planet Of The Ood resumed on September
4th, when the Hynix Building in Newport served as the main entrance of
Ood Operations. Cast and crew then shifted to the Johnsey Estates in the
Mamhilad Park Industrial Estate at Pontypool, where scenes inside
Warehouse 15 were recorded. This work continued to the next day, when
the Johnsey Estates also provided the corridor outside the Ood cells. An
additional shot in Halpen's office, of the Doctor and Donna in
restraints, was then filmed at Hensol Castle in Hensol on September 7th.
Work on Planet Of The Ood wrapped up two months later, on
November 16th. The decision to shift the episode back in the broadcast
schedule had necessitated a revision to the TARDIS scene, delaying its
recording. This was now completed at Upper Boat, alongside various
insert shots.